Contact lenses have been used commercially for vision improvement since at least the 1950s. The first contact lenses were made of hard materials and as such were somewhat uncomfortable to users. Modern lenses have been developed that are made of softer materials, typically hydrogels and particularly silicone hydrogels. Silicone hydrogels are water-swollen polymer networks that have high oxygen permeability and surfaces that can be more hydrophobic than hydrophilic.
Others have tried to make silicone hydrogel contact lenses more hydrophilic by applying hydrophilic coatings thereto. For example, it has been disclosed that silicone hydrogel lenses can he made more compatible with ocular surfaces by applying plasma coatings to the lens, and treating the lenses with reactive hydrophilic polymers.
Incorporation of internal hydrophilic wetting agents such as PVP and poly-2-ethyl-2-oxazoline, and polymerizable surfactants into a silicone hydrogel reaction mixture has been disclosed.
High molecular weight hydrophilic polymers have been used as internal wetting agents (IWA) in silicone hydrogel lenses, however, such polymers may be difficult to solubilize in reaction mixtures that contain silicones. In order to solubilize these wetting agents, compatibilizing components must be used. These compatibilizing components must be prepared in a separate step and then subsequently mixed with the remaining ingredients of the silicone hydrogel formulation. This additional step (or steps) increases the cost and the time it takes to produce these lenses.
Therefore it would be advantageous to find a lens formulation that does not require the use of surface treatment to provide eye wettability and resistance to surface depositions.